The molecules mediating GBS adherence to epithelial cells are currently unknown. Both lipoteichoic acid and proteins have been proposed as adhesins of CBS for adherence to epithelial cells; data regarding their roles are not conclusive. To my knowledge, no molecules have been proposed as adhesin receptors on epithelial cells as targets for CBS adherence. Fibronectin and other extracellular matrix (ECM) proteins, including laminin and collagens, act as adhesin receptors for multiple pathogens, including enterobacterial fimbrial binding proteins (types 3, I, S, P, Dr, and curli fimbriae), Yersinia spp., Staphylococcus aureus, Group A Streptococci (24), and Streptococcus dysgalactiae (11). It has been previously shown that CBS do not bind to soluble fibronectin (2) or collagen (22). I have recently obtained preliminary data that demonstrate that CBS bind to fibronectin when it is bound to a solid substrate. I hypothesize that CBS adhere to fibronectin via a specific molecule(s), and that this molecule(s) mediates adherence of CBS to epithelial cells. The following proposal will utilize the adherence of CBS and of CBS surface molecules to solid phase fibronectin together with transposon mutagenesis and cosmid cloning techniques to characterize the interaction of CBS to fibronectin interaction and to clone the gene(s) responsible for adherence of CBS to fibronectin. Mutants deficient in adherence to fibronectin will be generated, and used to study the relationship of fibronectin adhesins to CBS adherence to epithelial cells.